1. Technical Field
The present invention relates in general to computer based systems for product configuration management in the manufacture of complex products and in particular to methods and systems for defining a product or End Item Configuration for complex end items which involve special engineering design to modify a basic end item to meet specific customer requirements. Still more particularly, the present invention relates to a method and system for tracking multiple as designed end item configurations and their resultant effects on the basic end item.
2. Description of the Related Art
Computer based manufacturing systems are well known in the art. One function such systems typically provide is the tracking of engineering changes which may affect various end item configurations. For example, permanent changes to a basic end item which reduce cost or improve the basic end item are generally tracked in a time oriented manner. Additionally, changes to routings for basic items may occur as permanent changes which may or may not be caused by changes to the basic end item. Additionally, selected end item configurations may be especially created for specific customer contracts and may include changes which are considered as "transient" changes which are made to a basic End Item Configuration for one contract and may or may not be applicable to other contracts. Finally, routings for contracted end item configurations which are considered "transient" changes to the routings specifically for a particular configuration as modified for a customer contract.
Changes to a basic end item are generally incorporated in all Contract End Item configurations when the Contract End Item configurations are initially created. Subsequent changes to a basic end item are not automatically incorporated in the Contract End Item configurations. For example, for repeat orders, a customer may request certain changes to the previously contracted configuration. Appropriate version control techniques are needed to keep track of all changes to a contract End Item Configuration. The term "parallel version control" is generally used in the computer based manufacturing environment to describe this requirement. Parallel versions of an item are independent and concurrently active versions of different configurations of an item. These parallel versions are utilized to maintain a chronological history of all revisions made to each configuration of the same item.
In prior art systems the tracking of "as built" configurations has been accomplished and automated to some degree by a technique of "pegging" parts requirements to specific customer contracts. The recording of actual parts which were used to build a specific end item for a specific customer contract is known as "as built" configuration of the end item. Proper recording and management of "as designed" end item configurations continues to be a complex manual process.
Most existing bill of material systems require different product configurations to be redefined in separate hierarchies from the end item down through all non-standard components. More advanced bill of material systems often provide a multi-level end item effectivity which requires that non-standard items and/or components be relabeled for each new configuration.
Traditionally, most commercially available software in computer based manufacturing systems utilizes "date effectivity" for tracking engineering changes which modify product configurations over time. One such example is the COPICS (Communications Oriented Product Information and Control System) family of products and the MAPICS (Manufacturing Accounting and Production Information Control System) family of products both manufactured by International Business Corporation /f Armonk, N.Y. Version control of product configurations by "effective date" is suitable for tracking improvements or other "permanent" changes made to mass produced standard products but is generally unsuitable for tracking custom built product configurations.
More recently, some of the commercially available products utilized in computer based manufacturing systems have been modified for "serial number effectivity" in order to track "as built" product configurations, primarily to satisfy statutory accounting requirements. One example of such a product is the COPICS Defense product manufactured by International Business Machines Corporation. Such modified software products replace "from/to" dates by "from/to" serial numbers and use "pegged requirements" to connect detail component requirements to serially numbered end products. The "pegging" technique provides an upward traceability from components to assemblies, all the way up to the end product requirements stated in the master production schedule. However, none of the commercially available software products can distinguish between "permanent" changes made to a basic product and "transient" changes made to the basic product to satisfy specific customer requirements.
Thus, it should be apparent that a need exists for a method and system which permits product configuration management in a computer based manufacturing system which can maintain bills of material for item variations independently of the configurations which utilize those materials.